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Abstract:

The absorbent article according to the present invention includes a
laminate structure including cover, transfer layer, core and barrier, the
absorbent core having a first central region and second region
concentrically surrounding the first region.

Claims:

1. An absorbent article comprising:a liquid pervious cover layer;a liquid
impervious barrier layer;an absorbent core arranged between the cover
layer and barrier layer;a transfer layer arranged between the cover layer
and the core;a longitudinally extending centerline;a transversely
extending centerline;wherein the absorbent article has a thickness less 5
mm, a rewet less than 1 g and a lateral rigidity less than 1000 g.

2. The absorbent article according to claim 1, wherein the absorbent
article has a thickness less than 4 mm, a rewet less than 0.5 g and a
lateral rigidity less than 950 g.

3. The absorbent article according to claim 2, wherein the absorbent
article has a thickness less 3.5 mm, a rewet less than 0.25 g and a
lateral rigidity less than 875 g.

4. The absorbent article according to claim 3, wherein the absorbent core
has a first region and a second region concentrically surrounding the
first region.

5. The absorbent article according to claim 4, wherein the first region
has a basis weight in the range of 7.5 gsm to 385 gsm and wherein the
second region has a basis weight in the range of 150 gsm to 450 gsm.

6. The absorbent article according to claim 5, wherein the basis weight of
the second region is greater than the basis weight of the first region.

7. The absorbent article according to claim 6, wherein the basis weight of
the first region is about 5% to 85% the basis weight of the second
region.

8. The absorbent article according to claim 7, wherein the first region
extends along the longitudinally extending centerline and is
symmetrically arranged with respect to the longitudinally extending
centerline.

9. The absorbent article according to claim 8, wherein the first region
extends over about 5% to 30% of the surface area of the core.

10. The absorbent article according to claim 8, wherein the second region
extends over about 70% to about 95% of the surface area of the core.

11. An absorbent article comprising:a liquid pervious cover layer;a liquid
impervious barrier layer;an absorbent core arranged between the cover
layer and barrier layer;a transfer layer arranged between the cover layer
and the core;a longitudinally extending centerline;a laterally extending
centerline;wherein the absorbent core has a first region and second
region concentrically surrounding the first region, the first region
having a first basis weight and the second region having a second basis
weight, the first basis weight being less than the second basis weight,
the first basis weight being in the range of between 7.5 gsm and 385 gsm
and the second basis weight being in the range of between 150 and 450,
wherein the basis weight of the first region is about 5% to about 85% the
basis weight of the second region.

12. The absorbent article according to claim 11, wherein the first region
extends along the longitudinally extending centerline of the absorbent
article and is symmetrically arranged with respect to the longitudinally
extending centerline, the first region extending over about 5% to 30% the
surface area of the core and the second region extending over about 70%
to 95% of the core.

13. The absorbent article according to claim 12, wherein the absorbent
core comprises between about 75% to 100% cellulose fibers by weight and
0% to 25% superabsorbent by weight.

14. The absorbent article according to claim 13, wherein the absorbent
article has a thickness less than 5 mm, a rewet value of less than 1 g,
and a lateral stiffness of less than 1000 g.

[0002]Externally worn, sanitary absorbent napkins are one of many kinds of
feminine protection devices currently available. The development of
materials having a high liquid absorption capacity per unit volume has
allowed the required overall thickness of sanitary napkins to be reduced,
thereby providing a product which is more comfortable and less obtrusive
to wear. Sanitary napkins of this type, i.e. napkins having a thickness
of less than five millimeters, are commonly referred to "ultrathin"
sanitary napkins and conventionally have a laminate construction
including a body-facing liquid permeable layer, an absorbent core layer
or layers, and a liquid impermeable garment facing layer. Due to the
laminate construction of a conventional ultrathin napkins, and the
relatively high density of some of the constituent layers thereof,
ultrathin napkins do not readily conform to the contours of the body.
Rather, such napkins tend to fold rather than conform to the body,
thereby leaving gaps between the body and the body-facing surface of the
napkin. These gaps can lead to leakage of menstrual fluid before the
napkin has an opportunity to absorb the same. In addition, the tendency
of an ultrathin napkin to fold during use can cause discomfort to these
user at those locations where the user's body comes in contact with the
folded portions of the napkin.

[0003]The inventors of the present invention have discovered a sanitary
napkin construction that overcomes the shortcomings of ultrathin sanitary
napkins described above and more particularly a napkin that provides
enhanced body confirmation and superior fluid handling characteristics.

SUMMARY OF THE INVENTION

[0004]In view of the foregoing, the present invention provides, according
to a first aspect of the invention, an absorbent article including a
liquid pervious cover layer, a liquid impervious barrier layer, an
absorbent core arranged between the cover layer and barrier layer, a
transfer layer arranged between the cover layer and the core, a
longitudinally extending centerline, a transversely extending centerline,
the absorbent article having a thickness less than 5 mm, a rewet less
than 1 g, and a lateral rigidity less than 1000 g.

[0005]The present invention provides, according to a second aspect of the
invention, an absorbent article including a liquid pervious cover layer,
a liquid impervious barrier layer, an absorbent core arranged between the
cover layer and barrier layer, a transfer layer arranged between the
cover layer and the core, a longitudinally extending centerline, a
laterally extending centerline, the absorbent core having a first region
and second region concentrically surrounding the first region, the first
region having a first basis weight and the second region having a second
basis weight, the first basis weight being less than the second basis
weight, the first basis weight being in the range of between 7.5 gsm and
385 gsm and the second basis weight being in the range of between 150 gsm
and 450 gsm, the basis weight of the first region being about 5% to about
85% the basis weight of the second region.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]Examples of embodiments of the present invention will now be
described with reference to the drawings, in which:

[0007]FIG. 1 is a perspective view of a sanitary napkin in accordance with
an embodiment of the present invention;

[0008]FIG. 2 is an exploded view of the sanitary napkin shown in FIG. 1,
according to a first embodiment of the invention, showing the constituent
layers thereof;

[0009]FIG. 3 is an exploded view of the sanitary napkin shown in FIG. 1,
according to a second embodiment of the invention, showing the
constituent layers thereof;

[0010]FIG. 4 is a top plan view of the core layer of the sanitary napkin
shown in FIG. 1 showing the first and second concentric regions thereof;

[0014]FIG. 8 is a schematic view showing an apparatus for making the core
layer shown in FIGS. 3-7;

[0015]FIG. 9 is a detailed perspective view of a portion of the apparatus
shown in FIG. 8;

[0016]FIG. 10 is a sectional view of the apparatus shown in FIG. 8 taken
along line 10-10 thereof;

[0017]FIG. 11 is a detailed elevation view of a portion of the apparatus
shown in FIG. 8;

[0018]FIG. 12 is a detailed perspective view of a portion of the apparatus
shown in FIG. 8;

[0019]FIG. 13 is a front elevation view of an apparatus for measuring
lateral rigidity of an absorbent article together with an absorbent
article mounted in the device for testing;

[0020]FIG. 14 is a front elevation view of the apparatus shown in FIG. 13;

[0021]FIG. 15 is a top elevation view of the apparatus shown in FIG. 13;
and

[0022]FIG. 16 is a top elevation view of a test plate used to conduct the
Rewet Potential Test Method described herein.

DETAILED DESCRIPTION OF THE INVENTION

[0023]Referring to FIGS. 1 and 2, there is shown an embodiment of the
present invention, a feminine sanitary napkin 10.

[0024]The sanitary napkin 10 has a main body 22 with a first transverse
side 26 defining a front portion thereof and a second transverse side 28
defining a rear portion thereof. The main body also has two longitudinal
sides, namely a longitudinal side 30 and a longitudinal side 32. The
sanitary napkin 10 preferably has a thickness less than 5 mm, more
preferably less than 4 mm, and most preferably less than 3.5 mm according
to the test method set forth herein ("Procedure for Measuring the
Thickness of an Absorbent Article").

[0025]The sanitary napkin 10 has a longitudinal centerline 34 that is an
imaginary line bisecting the sanitary napkin 10 in two identical halves.
The main body 22 also has an imaginary transverse centerline 36
perpendicularly arranged relative to the longitudinal centerline 34.

[0026]As depicted in FIG. 2, the main body 22, according to a first
embodiment of the invention, is of a laminate construction and includes a
fluid-permeable cover layer 42, a transfer layer 43, an absorbent core 44
and a fluid-impervious barrier layer 50.

[0027]As depicted in FIG. 3, the main body 22, according to a second
embodiment of the invention, is of a laminate construction and includes a
fluid-permeable cover layer 42, an absorbent core 44, and a
fluid-impervious barrier layer 50.

[0028]Referring to FIGS. 4-7, the absorbent core 44 includes a first
region 70 and second region 72 concentrically surrounding the first
region 70. The first region 70 has a basis weight in the range of between
7.5 gsm (g/m2) and 385 gsm (g/m2) and the second region 72 have
a basis weight in the range of between 150 gsm and 450 gsm. The basis
weight of the first region 70 is selected such that is less than the
basis weight of the second region 72. In particular, the basis weight of
the first region 70 is selected such that it is has a basis weight of
about 5% to about 85% the basis weight of the second region 72.

[0029]As shown in FIG. 4 the first region 70 extends along the
longitudinally extending centerline 34 of the sanitary napkin 10 and is
arranged symmetrically with respect to the longitudinally extending
centerline 34. Preferably the first region 70 extends over about 5% to
about 30% the surface area of the core 44 and the second region 72
extends over about 70% to 95% of the core. The absorbent core 44
preferably has a substantially uniform thickness between about 0.5 mm and
about 2.5 mm.

[0030]In a preferred embodiment of the invention, the absorbent core 44
comprises between about 75% to 100% cellulose fibers by weight and 0% to
25% superabsorbent polymer by weight. In a particularly preferred
embodiment, the first region 70 and the second region have 72 the same
identical material composition. Also, preferably, the first region 70 and
second region 72 are composed of a single layer of material, that is the
first region 70 and second region 72 are not formed by layering two
distinct layers one on top of another.

[0031]In the particular embodiment of the invention shown in FIG. 4, the
first region 70 of the absorbent core 44 is shaped such that a perimeter
76 thereof has first curvilinear first end portion 78 and an opposed
curvilinear end portion 80, each of the end portions being interconnected
by opposed arcuate side portions 82 and 84. In this manner, the first
region 70 is widest at its most distal portions relative to the
intersection of the longitudinal centerline 34 and transverse centerline
36 and is most narrow at the intersection of the longitudinal centerline
34 and transverse centerline 36.

Main Body--Cover Layer

[0032]The cover layer 42 may be a relatively low density, bulky, high-loft
non-woven web material. The cover layer 42 may be composed of only one
type of fiber, such as polyester or polypropylene or it may include a
mixture of more than one fiber. The cover may be composed of bi-component
or conjugate fibers having a low melting point component and a high
melting point component. The fibers may be selected from a variety of
natural and synthetic materials such as nylon, polyester, rayon (in
combination with other fibers), cotton, acrylic fiber and the like and
combinations thereof. Preferably, the cover layer 42 has a basis weight
in the range of about 10 gsm to about 75 gsm.

[0033]Bi-component fibers may be made up of a polyester layer and a
polyethylene sheath. The use of appropriate bi-component materials
results in a fusible non-woven fabric. Examples of such fusible fabrics
are described in U.S. Pat. No. 4,555,430 issued Nov. 26, 1985 to
Chicopee. Using a fusible fabric increases the ease with which the cover
layer may be mounted to the absorbent layer and/or to the barrier layer.

[0034]The cover layer 42 preferably has a relatively high degree of
wettability, although the individual fibers comprising the cover may not
be particularly hydrophilic. The cover material should also contain a
great number of relatively large pores. This is because the cover layer
42 is intended to take-up body fluid rapidly and transports it away from
the body and the point of deposition. Therefore, the cover layer
contributes little to the time taken for the napkin to absorb a given
quantity of liquid (penetration time).

[0035]Advantageously, the fibers that make up the cover layer 42 should
not lose there physical properties when they are wetted, in other words
they should not collapse or lose their resiliency when subjected to water
or body fluid. The cover layer 42 may be treated to allow fluid to pass
through it readily. The cover layer 42 also functions to transfer the
fluid quickly to the underlying layers of the absorbent article. Thus,
the cover layer 42 is advantageously wettable, hydrophilic and porous.
When composed of synthetic hydrophobic fibers such as polyester or
bi-component fibers, the cover layer 42 may be treated with a surfactant
to impart the desired degree of wettability.

[0036]In one preferred embodiment of the present invention the cover is
made from a 25 gsm thermal bonded polypropylene fiber nonwoven of the
type commercially available from Polystar Company, Salvador, BA, Brazil,
commercially known as Multidenier Telao 25 cover.

[0037]Alternatively, the cover layer 42 can also be made of polymer film
having large pores. Because of such high porosity, the film accomplishes
the function of quickly transferring body fluid to the underlying layers
of the absorbent article. A suitable cover material of this type is
commercially found on the STAYFREE Dry Max Ultrathin product distributed
by the Personal Products Company Division of McNeil-PPC, Inc., Skillman,
N.J.

[0038]The cover layer 42 may be embossed to the remainder of the absorbent
core 44 in order to aid in promoting hydrophilicity by fusing the cover
to the next layer. Such fusion may be effected locally, at a plurality of
sites or over the entire contact surface of cover layer 42 and absorbent
core 44. Alternatively, the cover layer 42 may be attached to the
absorbent core 44 by other means such as by adhesion.

Main Body--Transfer Layer

[0039]Adjacent to the cover layer 42 on its inner side and bonded to the
cover layer 42 is the transfer layer 43. The transfer layer 43 provides
the means of receiving body fluid from the cover layer 42 and holding it
until the underlying absorbent core 44 has an opportunity to absorb the
fluid, and therefore acts as a fluid transfer or acquisition layer. The
transfer layer 43 is, preferably, more dense than and has a larger
proportion of smaller pores than the cover layer 42. These attributes
allow the transfer layer 43 to contain body fluid and hold it away from
the outer side of the cover layer 42, thereby preventing the fluid from
rewetting the cover layer 42 and its surface. However, the transfer layer
is, preferably, not so dense as to prevent the passage of the fluid
through the layer 43 into the underlying absorbent core 44.

[0040]The transfer layer 43 be composed of fibrous materials, such as wood
pulp, polyester, rayon, flexible foam, or the like, or combinations
thereof. The transfer layer 43 may also comprise thermoplastic fibers for
the purpose of stabilizing the layer and maintaining its structural
integrity. The transfer layer 43 may be treated with surfactant on one or
both sides in order to increase its wettability, although generally the
transfer layer 43 is relatively hydrophilic and may not require
treatment. The transfer layer 43 is preferably bonded or adhered on both
sides to the adjacent layers, i.e. the cover layer 42 and the underlying
absorbent core 44.

[0041]Materials particularly suitable for use in the first absorbent layer
43, which the inventors have found contribute to reducing the rewet
potential have a density in the range of about 0.04 to 0.10 g/cc, a basis
weight in the range from about 60 to 150 gsm and a thickness in the range
of about 1 to 3 mm. Examples of suitable materials for the transfer layer
are through air bonded pulp sold by Buckeye of Memphis, Tenn., under the
designation VIZORB 3008, which has a basis weight of 110 gsm, VIZORB
3042, which has a basis weight of 100 gsm, VIZORB 3010, which has a basis
weight of 90 gsm and others.

Main Body--Absorbent Core

[0042]In one preferred embodiment of the invention, the absorbent core 44
is a blend or mixture of cellulosic fibers and superabsorbent disposed
therein. Cellulosic fibers that can be used in the absorbent core 44 are
well known in the art and include wood pulp, cotton, flax and peat moss.
Wood pulp is preferred. Pulps can be obtained from mechanical or
chemi-mechanical, sulfite, kraft, pulping reject materials, organic
solvent pulps, etc. Both softwood and hardwood species are useful.
Softwood pulps are preferred. It is not necessary to treat cellulosic
fibers with chemical debonding agents, cross-linking agents and the like
for use in the present material. Some portion of the pulp may be
chemically treated as discussed in U.S. Pat. No. 5,916,670 to improved
flexibility of the product. The flexibility of the material may also be
improved by mechanically working the material or tenderizing the
material.

[0043]The absorbent core 44 can contain any superabsorbent polymer (SAP),
which are well known in the art. For the purposes of the present
invention, the term "superabsorbent polymer" (or "SAP") refers to
materials, which are capable of absorbing and retaining at least about 10
times their weight in body fluids under a 0.5 psi pressure. The
superabsorbent polymer particles of the invention may be inorganic or
organic crosslinked hydrophilic polymers, such as polyvinyl alcohols,
polyethylene oxides, crosslinked starches, guar gum, xanthan gum, and the
like. The particles may be in the form of a powder, grains, granules, or
fibers. Preferred superabsorbent polymer particles for use in the present
invention are crosslinked polyacrylates, such as the product offered by
Sumitomo Seika Chemicals Co., Ltd. Of Osaka, Japan, under the designation
of SA70N and products offered by Stockhausen Inc.

[0044]In one preferred embodiment of the invention the absorbent core 44
includes between 50% and 100% cellulose pulp by weight and 0% and 50%
superabsorbent polymer by weight.

[0046]A description of the method of making the absorbent core according
to the present invention will now be provided with reference to FIGS.
8-12 which depicts an apparatus 200 for making the absorbent core
structure according to the present invention. The pulp used to form the
absorbent core 44 is a bleached softwood pulp, produced by a Kraft
process. The pulp is provided by the manufacturer as a pulp board 202 in
rolled form, the roll identified by the reference numeral 204 in FIG. 8.
The pulp board 202 is conveyed from the roll 204 to a device 206 for
grinding the pulp board 202 into fibrous pulp 205. The fibrous pulp 205
is released from the grinding device 206 into a chamber 208 for holding
the fibrous pulp 205. The apparatus 200 may further optionally include a
device 207 for introducing superabsorbent polymer into the chamber 208 to
thereby form a fibrous pulp and superabsorbent mixture. Any conventional
device suitable for this purpose, and known to those of skill in the art,
may be used for introducing the superabsorbent into the chamber 208.

[0047]The chamber 208 has a partially open bottom portion 211 that
communicates with a rotating forming drum 210. The rotating forming drum
210 has a plurality of molds 212 mounted thereto. As the forming drum 210
rotates, each of the molds 212 are sequentially arranged in communication
with the open portion 211 of the chamber 208 to thereby receive fibrous
pulp 205 from the chamber 208. In FIG. 8, the forming drum 210 rotates in
a counterclockwise manner during operation of the apparatus 200. As shown
in FIG. 10, the forming drum 210 includes a portion 214 that is under
vacuum. As shown in FIGS. 9 and 10, the mold 212 includes a porous screen
217 structure in the shape of the second region 72 of the core 44. As the
mold 212 passes over portion 214 of the forming drum 210 the vacuum
functions to draw the fibrous pulp 205 from the chamber 208 into the mold
212 by drawing air through the porous screen 217 of the mold 212.

[0048]As shown in detail in FIG. 10, the mold 212 includes a nonporous
mounting plate portion 215 that surrounds the porous screen 217 portion
of the mold 212. As best seen in FIG. 10, the mounting plate portion 214
of the mold 212 is mounted to the periphery 219 of the forming drum 210,
thereby enabling each of the molds 212 to rotate with the rotating
forming drum 210. The porous screen 217 portion of the mold 212 is
arranged in the shape of the second region 72 of the core 44. The mold
212 further includes a nonporous central portion 218 in the shape of the
first region 70. The nonporous central portion 218 has a height that is
less than the height of the mounting plate portion 214. The structure of
the mold 212 described above, during use, causes a greater amount of
fibrous pulp 205 to be drawn into the porous screen 217 portion of the
mold 212 relative to the amount of fibrous pulp 205 drawn into the
nonporous central portion 218.

[0049]After the mold 212 is rotated under the partially open bottom
portion 211 of the chamber 208, the mold 212 is further rotated by the
rotating forming drum 210. As shown in FIG. 11, the rotating forming drum
210 includes a portion 221 that expels air outwardly from within the drum
210. The portion 221 of the drum 210 functions to expel the core 44
structure formed within the mold 212 onto a belt 222. The belt 222
functions to convey the core 44 to a first calendar roll 224. The
calendar roll 224 functions to reduce the thickness of the core 44. As
shown in FIG. 12, the core 44 is then further conveyed by the belt 222 to
a second calendar roll 226 that functions to further reduce the thickness
of the core 44 to its final thickness. As shown in FIG. 12, after passing
through the second calendar roll 226, the first 70 and second 72 regions
of the core 44 have a uniform thickness but have different basis weights.

Main Body--Barrier Layer

[0050]Underlying the absorbent core 44 is a barrier layer 50 comprising
liquid-impervious film material so as to prevent liquid that is entrapped
in the absorbent core 44 from egressing the sanitary napkin and staining
the wearer's undergarment. The barrier layer 50 is preferably made of
polymeric film, although it may be made of liquid impervious,
air-permeable material such as repellent-treated non-woven or micropore
films or foams.

[0051]The barrier layer may be breathable, i.e., permits vapor to
transpire. Known materials for this purpose include nonwoven materials
and microporous films in which microporosity is created by, inter alia,
stretching an oriented film. Single or multiple layers of permeable
films, fabrics, melt-blown materials, and combinations thereof that
provide a tortuous path, and/or whose surface characteristics provide a
liquid surface repellent to the penetration of liquids may also be used
to provide a breathable backsheet. The cover layer 42 and the barrier
layer 50 are joined along their marginal portions so as to form an
enclosure or flange seal that maintains the absorbent core 44 captive.
The joint may be made by means of adhesives, heat-bonding, ultrasonic
bonding, radio frequency sealing, mechanical crimping, and the like and
combinations thereof.

[0052]Positioning adhesive may be applied to a garment facing side of the
barrier layer for securing the napkin 10 to a garment during use. The
positioning adhesive may be covered with removable release paper so that
the positioning adhesive is covered by the removable release paper prior
to use.

[0053]Absorbent articles of this invention may or may not include wings,
flaps or tabs for securing the absorbent article to an undergarment.
Wings, also called, among other things, flaps or tabs, and their use in
sanitary protection articles is described in U.S. Pat. No. 4,687,478 to
Van Tilburg; U.S. Pat. No. 4,589,876 also to Van Tilburg, U.S. Pat. No.
4,900,320 to McCoy, and U.S. Pat. No. 4,608,047 to Mattingly. The
disclosures of these patents are incorporated herein by reference in
their entirety. As disclosed in the above documents, wings are generally
speaking flexible and configured to be folded over the edges of the
underwear so that the wings are disposed between the edges of the
underwear.

[0054]The absorbent article of the present invention may be applied to the
crotch by placing the garment-facing surface against the inside surface
of the crotch of the garment. Various methods of attaching absorbent
articles may be used. For example, chemical means, e.g., adhesive, and
mechanical attachment means, e.g., clips, laces, ties, and interlocking
devices, e.g., snaps, buttons, VELCRO (Velcro USA, Inc., Manchester,
N.H.), zipper, and the like are examples of the various options available
to the artisan.

[0055]Adhesive may include pressure sensitive adhesive that is applied as
strips, swirls, or waves, and the like. As used herein, the term
pressure-sensitive adhesive refers to any releasable adhesive or
releasable tenacious means. Suitable adhesive compositions, include, for
example, water-based pressure-sensitive adhesives such as acrylate
adhesives. Alternatively, the adhesive composition may include adhesives
based on the following: emulsion or solvent-borne adhesives of natural or
synthetic polyisoprene, styrene-butadiene, or polyacrylate, vinyl acetate
copolymer or combinations thereof, hot melt adhesives based on suitable
block copolymers--suitable block copolymers for use in the invention
include linear or radial co-polymer structures having the formula (A-B)x
wherein block A is a polyvinylarene block, block B is a poly(monoalkenyl)
block, x denotes the number of polymeric arms, and wherein x is an
integer greater than or equal to one. Suitable block A polyvinylarenes
include, but are not limited to Polystyrene, Polyalpha-methylstyrene,
Polyvinyltoluene, and combinations thereof. Suitable Block B
poly(monoalkenyl) blocks include, but are not limited to conjugated diene
elastomers such as for example polybutadiene or polyisoprene or
hydrogenated elastomers such as ethylene butylene or ethylene propylene
or polyisobutylene, or combinations thereof. Commercial examples of these
types of block copolymers include Kraton® elastomers from Shell
Chemical Company, Vector® elastomers from Dexco, Solprene® from
Enichem Elastomers and Stereon® from Firestone Tire & Rubber Co.; hot
melt adhesive based on olefin polymers and copolymers where in the olefin
polymer is a terpolymer of ethylene and a co-monomers, such as vinyl
acetate, acrylic acid, methacrylic acid, ethyl acrylate, methyl acrylate,
n-butyl acrylate vinyl silane or maleic anhydride. Commercial examples of
these types of polymers include Ateva (polymers from AT plastics), Nucrel
(polymers from DuPont), Escor (from Exxon Chemical).

[0056]Where adhesive is used, a release strip may be applied to protect
the adhesive on the absorbent article prior to attaching the absorbent
article to the crotch. The release strip can be formed from any suitable
sheet-like material adheres with sufficient tenacity to the adhesive to
remain in place prior to use but which can be readily removed when the
absorbent article is to be used. Optionally, a coating may be applied to
release strip to improve the ease of removabilty of the release strip
from the adhesive. Any coating capable of achieving this result may be
used, e.g., silicone.

[0059]The absorbent article may include other known materials, layers, and
additives, such as, foam, net-like materials, perfumes, medicaments or
pharmaceutical agents, moisturizers, odor control agents, and the like.
The absorbent article can optionally be embossed with decorative designs.

[0060]The absorbent article may be packaged as unwrapped absorbent
articles within a carton, box or bag. The consumer withdraws the
ready-to-use article as needed. The absorbent article may also be
individually packaged (each absorbent article encased within an
overwrap).

[0061]Also contemplated by the present invention are asymmetrical and
symmetrical absorbent articles having parallel longitudinal edges, dog
bone- or peanut-shaped, as well as articles having a tapered construction
for use with thong-style undergarments. From the foregoing description,
one skilled in the art can ascertain the essential characteristics of
this invention, and without departing from the spirit and scope thereof,
can make various changes and modifications. Embodiments set forth by way
of illustration are not intended as limitations on the variations
possible in practicing the present invention.

Test Procedures

[0062]Absorbent articles according to the present invention have a unique
combination of functional properties, in particular articles according to
the present invention are particularly flexible in the transverse
direction and also provide superior fluid handling characteristics. A
number of test procedures are described below that highlight the
functional properties of absorbent articles according to the present
invention. Prior to conducting any of the described test procedures
described below the test product should be conditioned for two hours at
21±1° C. and 50±2% humidity.

Procedure for Measuring the Thickness of an Absorbent Article

[0063]Preferred embodiments of the present invention relate to
"ultra-thin" sanitary napkins. "Ultra-thin" sanitary napkins as defined
herein are those sanitary napkins that have a thickness of less than 5 mm
and more preferably less than 4 mm according to the test method set forth
herein.

[0064]The apparatus required to measure the thickness of an absorbent
article is a footed dial (thickness) gauge with stand, available from
Ames, with a 2'' (5.08 cm) diameter foot at a pressure of 0.07 psig and a
readout accurate to 0.001'' (0.00254 cm). A digital type apparatus is
preferred. If the absorbent article sample is individually folded and
wrapped, the sample is unwrapped and carefully flattened by hand. The
release paper is removed from the product sample and it is repositioned
back gently across the positioning adhesive lines so as not to compress
the sample, ensuring that the release paper lies flat across the sample.
Flaps (if any) and release paper are not considered when taking the
thickness.

[0065]The foot of the gauge is raised and the product sample is placed on
the anvil such that the foot of the gauge is approximately centered over
the intersection of the longitudinally extending centerline and
transversely extending centerline on the product sample. When lowering
the foot, care must be taken to prevent the foot from dropping onto the
sample or from undue force being applied. A load of 0.07 p.s.i.g. is
applied to the sample and the read out is allowed to stabilize for
approximately 5 seconds. The thickness reading is then taken. This
procedure is repeated for at least five product samples and the average
thickness is then calculated.

Procedure for Measuring Rewet Potential

[0066]The rewet potential is a measure of the ability of a napkin or other
article to hold liquid within its structure when the napkin contains a
relatively large quantity of liquid and is subjected to external
mechanical pressure. Absorbent articles according to the present
invention preferably have a rewet value of less than 1.0 g, more
preferably less than 0.5 g, and most preferably less than 0.25 g. The
rewet potential is determined and defined by the following procedure.

[0067]The instruments required for the Rewet Potential test include an
orifice plate (described below), a quantity of 3 inch×4 inch
rectangles of Whatman #1 filter paper (Whatman Inc., Clifton, N.J.), a
calibrated electronic repeater pipette (HandyStep Electronic Repeating
Pipet, Brandtech) with a 50 mL combi-syringe (or combi-tip) capable of
delivering 5-10 mL at a rate of approximately 4 mL/s, and a weighing
machine or balance capable of weighing to an accuracy of ±0.01 g, a
standard weight of 2.22 kg (4.8 pounds) having dimensions 5.1 cm (2
inches) by 10.2 cm (4.0 inches) by approximately 5.4 cm (2.13 inches)
which applies a pressure of 4.14 kPa (0.6 psi) over the 5.1 cm by 10.2 cm
(2 inches by 4 inches) surface. The orifice plate 300, as shown in FIG.
16, consists of a 7.6 cm×25.4 cm plate of 1.3 cm thick
polycarbonate with an elliptical orifice 302 in its center. The
elliptical orifice 302 measures 3.8 cm along its major axis and 1.9 cm
along its minor axis. The longitudinal axis of the elliptical orifice 302
is arranged parallel to the longitudinal axis of the product to be
tested.

[0068]A synthetic test fluid used in replacement of human menses due to
its ease in preparation and accessibility of the ingredients. The fluid
is prepared by dissolving each of the following components into distilled
water. Care should be taken to ensure that components are well dissolved.
A rotating blade mixer or a magnetic stirrer should be used for mixing
the components. In a large enough container, add the following
components, making sure that the component is dissolved before adding the
next one:

[0069]A 50 mL combi-syringe (or combi-tip), placed on a repeater pipette,
is filled with the test fluid, positioned vertically and the tip placed
approximately 1 inch from the surface of the product and above the center
of the elliptical hole of the plate. The article should be arranged such
that the intersection of the longitudinally extending and transversely
extending centerlines is positioned in the center of the hole. Then, 7 mL
of test fluid is insulted to the article at a rate of approximately 4
mL/s.

[0070]After the test fluid is applied within the orifice plate 300 and as
soon as the cover layer of the napkin first appears through the top
surface of the fluid, the stopwatch is started and an interval of 5
minutes is measured.

[0071]After 5 minutes have elapsed, the orifice plate 300 is removed and
the napkin is positioned on a hard level surface with the cover layer
facing upwards.

[0072]A fifteen (15) layer stack of the pre-weighed filter paper is placed
on and centered over the wetted area and the standard 2.22 kg weight is
placed on top of the filter paper. The filter paper and the weight are
arranged over the absorbent article such that they are centered over the
area to which the fluid was applied. The filter paper and the weight are
arranged such that their longer dimensions are aligned with the
longitudinal direction of the product. Immediately after placing the
paper and weight on the product, the stopwatch is started and after a 3
minute interval has elapsed the standard weight and filter paper are
quickly removed. The wet weight of the filter paper is measured and
recorded to the nearest 0.01 grams. The rewet value is then calculated as
the difference in grams between the weight of the wet 15 layers of filter
paper and the dry 15 layers of filter paper.

[0073]The measurement should have at least five replicates and, if
necessary, the weight is wiped clean before each run. The average rewet
value is then calculated from the five measured values and recorded as
the average rewet value.

Procedure for Measuring Lateral Rigidity

[0074]Absorbent articles according to the present invention preferably
have a relatively low lateral rigidity thereby promoting comfort during
use. In particular, articles according to the present invention
preferably have a lateral rigidity of less than 1000 g, more preferably
less than 900 g, and most preferably less than 875 g.

[0075]A method for measuring the lateral rigidity of an absorbent article
is described below. The apparatus 100 required for this measurement is
illustrated in FIGS. 13-15. The apparatus 100 includes two front metal
rods 102a (diameter=4.4 mm, length=102.2 mm), two rear metal rods 102b
(diameter=4.4 mm, length=102.2 mm), and one central metal rod 104
(diameter=2.4 mm, height=92.1 mm) mounted on a first Plexiglass
arc-shaped plate 106 (diameter=139.7 mm and height=37.9 mm), which serves
to hold the sanitary napkin 10. The napkin 10 (or other absorbent article
to be tested) should be arranged such that the intersection of the
longitudinally extending centerline 15 and transversely extending
centerline 17 is arranged in alignment with the central metal rod 104.

[0076]The two front metal rods 102a are spaced from one another by a
distance of 31.8 mm as measured from the center of one rod to the center
of the other rod. The two rear metal rods 102b are also spaced from one
another by a distance of 31.8 mm as measured from the center of one rod
to the center of the other rod. The distance between corresponding front
102a and rear 102b rods, i.e. the front and rear rods that are in front
to back alignment, is 12.7 mm.

[0077]The plate 106 is mounted on the base 108 of an inverted compression
load cell 110. A second Plexiglas arc-shaped plate 112 (diameter=139.7 mm
and height=37.9 mm) is placed upside down on the top part of the inverted
compression cell and used to compress the napkin 10 in the transverse
direction thereof. The load cell has a range of about 0.0 to about 2000.0
g and is used on an actuator and more specifically on an Instron Model
No. 1123 (Instron Engineering Corporation, Canton, Mass.).

[0078]Before starting the measurement, the napkin is removed from the
packaging and unfolded. The release paper is removed and talc powder is
sprinkled over the adhesive strips. Using a ruler and the central rod as
a guide, the initial position of the compression cell is adjusted so that
the distance between the surfaces of the plates 106 and 112 is 7.62 cm (3
inches). The napkin 10 is placed between the rods 102a, 102b, and 104, as
shown in the FIG. 7. The actuator is set so that during the compression
cycle, it will move down by 5.08 cm at a speed of 50 cm/min. The peak
force (g) measured during the first compression cycle is recorded as the
lateral rigidity of the sample. This procedure is repeated with five
different product samples and an average value is calculated.

EXAMPLES

[0079]Specific inventive examples of the present invention are described
below. Comparative examples are also described below. Each of the
inventive and comparative examples were subjected to the test methods
described above and the results of such tests are summarized in the Table
set forth below.

Inventive Example #1

[0080]An example of an ultrathin sanitary napkin according to the
invention was constructed as follows. The body facing cover layer was
constructed from a 25 gsm hot through air bonded nonwoven material
constructed from 100% hydrophilic polypropylene fibers, commercially
available form Polystar Company, Salvador, Brazil under the commercially
name of Multidenier Telao 25 cover. A 100 gsm transfer layer was arranged
below the cover layer, the transfer layer was formed from through air
bonded pulp sold by Buckeye of Memphis, Tenn., under the designation
VIZORB 3042. An absorbent core was arranged below the transfer layer and
was formed by the process described herein with reference to FIGS. 8-12.
The absorbent core had a first region with a surface area of 9700
mm2 and second region with a surface area of 2100 mm2. The
first region had a basis weight of 300 gsm and the second region had a
basis weight of 150 gsm. The absorbent core had a composition of 89% by
weight of pulp and 11% by weight of superabsorbent polymer. The pulp was
Golden Isles Fluff Pulp 420#HD 7% Moisture, commercially available from
GP Cellulose, Brunswick, Ga., USA. The superabsorbent polymer was Aqua
Keep SA70N commercially available from Sumitomo Seika Chemicals Co.,
Ltd., Osaka, Japan. A barrier layer was arranged below the core and was
formed from a 24 gsm polyethylene (PE 24 gsm) film commercially available
from Clopay do Brasil, Sao Paulo, SP, Brazil. Each of the layers of the
sanitary napkin were adhered to one another using a conventional hot melt
adhesive.

Comparative Example #1

[0081]Comparative Example #1 was constructed in the same manner as
Inventive Example #1 except that the absorbent core of Inventive Example
#1 was replaced with a core having the same material composition as the
core described with respect to Inventive Example #1 but having a uniform
basis weight of 300 gsm.

Inventive Example #2

[0082]Inventive Example #2 was constructed in the same manner as Inventive
Example #1 except that the cover layer thereof was replaced by the cover
layer found on the STAYFREE Ultrathin Drymax product distributed by
McNeil-PPC, Inc.

Comparative Example #2

[0083]Comparative Example #2 was constructed in the same manner as
Inventive Example #2 except that the core layer was replaced with a core
having the same material composition as the core described with respect
to Inventive Example #1 but having a uniform basis weight of 300 gsm.

[0084]Each of the inventive example and comparative example were tested
according to the test methods set forth herein and the results of such
testing are set forth in Table #1 below.

[0085]Applications of the absorbent article according to the present
invention for sanitary and other health-care uses can be accomplished by
any sanitary protection, incontinence, medical and absorbent methods and
techniques as are presently or prospectively known to those skilled in
the art. Thus, it is intended that the present application cover the
modifications and variations of this invention provided that they come
within the scope of the appended claims and their equivalents.